1. Field of the Invention
The present invention relates to the sheet feeding controlling system of general recording apparatus such as electrophotographic copying machines and printing apparatus.
2. Description of the Prior Art
An example of an electrophotographic copying machine will be given. For copying an original, the method wherein the cassette is loaded in the apparatus and a sheet of recording paper is fed from the cassette for each copying operation is now available, in addition to the method wherein recording paper is fed manually one by one. Such a cassette contains many recording sheets, and recently, this type of cassette system is employed in most of the electrophotographic copying machines. Generally, the recording papers of prescribed sizes such as B6, B5, B4, A5, A4 and A3 or such as 8".times.13", 81/2".times.14", 10".times.15", 11".times.17" and 11".times.81/2" are used for copying and the cassettes of such various sizes to accept the recording sheets of various sizes are available. Some of the recent electrophotographic copying machines have the feature that several different sized cassettes are loaded therein and with the operation of a selection button, the recording sheet is fed from the desired cassette. In another type wherein no cassette is used, different sized recording sheets of more than two types are loaded at fixed locations therein, and with the operation of a selection button, the recording sheet of desired size is used.
Now, since it is not advisable, from the view point of the size of the apparatus and the price thereof, to load recording sheets of all sizes in such types of recording apparatus, it is conventional in the small sized machine used generally that 2 to 3 types of different recording sheets are contained in the cassette for example and loaded therein. Therefore, when the recording sheet of desired size coincides with any one size of several sizes of loaded sheets, a simple operation of recording sheet size selection button is enough, but when they do not coincide, it is necessary to change the cassette to a cassette containing recording sheets of the desired size prior to the copying operation, and to operate the recording sheet size selection button so that the recording sheet can be fed from said changed cassette. In such cases, though it may be unavoidable to change the cassette, it is troublesome to operate the selection button further, and if such selecting operation is neglected carelessly, there is the danger that the recording may be done on the recording sheet the size of which is selected by the previous operator, and thus the copied material will not be useful in spite of changing the cassette.